Chrome and/or mineral tanned leathers are at present retanned with syntans, vegetable extracts and/or resins of various types. This is done to impart retan effects or characteristics which chrome and/or mineral tanned leather does not of itself possess. The effects or characteristics include: bleaching, dye assisting, plumping, increased weight, less shrinkage, better feel, better grain character, and buffability.
Conventional retan material generally imparts to chrome and/or mineral tanned leather a positive characteristic of rewetting and water absorption. Conventional leather lubricants applied as emulsions (fatliquors) generally add to this characteristic of wetting. Various materials such as: hydrophobic rubbers and resins, fluorocarbons, fatty chrome complexes, silicones, and waxes, are applied on top of conventional retan and fatliquor treatments to overcome the undesirable rewetting and water absorption characteristic imparted by these treatments. In many cases the result is sub-standard.
Known attempts to overcome this problem include the use of a fatliquor containing a polybasic acid ester (U.S. Pat. No. 2,950,950) and the use of a fatliquor containing an alkyl phosphate (U.S. Pat. No. 3,010,780). More recently, complete fatliquor systems incorporating alkyl phosphates as emulsifiers for leather oils have been developed to overcome the deficiencies of the above approaches.
All of the above systems are effective in lubricating leather, but do not supply a sufficient degree of internal water resistance unless used in excess. In order to achieve increased internal water resistance with the above systems, sufficient fatliquor must be added to penetrate the leather deeply, resulting in poor leather character and quality.
U.S. Pat. No. 2,454,542 to Bock discloses and claims polymeric alkylphenol condensates which are subsequently alkoxylated and phosphated. These compounds were prepared by condensing a C.sub.4 or higher alkyl substituted phenol and preferably at least an octylphenol. While there is a brief suggestion that a mixture of phenols can be employed, the only mixture mentioned is p-tert-amyl and p-diisobutylphenols. In any case the lowest alkylphenol which could be employed in such a mixture would be butylphenol, since the Bock reference specifically teaches a preferred lower limit of C.sub.8 alkylphenols, and an absolute lower unit of C.sub.4 alkylphenols.